A power plug is a power transfer device that connects electric equipment to a power source. A sudden outage can cause serious loss of life and property when power is supplied to important equipment such as a data center requiring continuous power supply, a medical apparatus or instruments in an operating room, etc. Therefore, there is a need for a safe, reliable, simple and effective power source connection. If a power plug loosens or drops out when shaken or collided by external force, this will lead to poor contact or no contact and result in a power outage.